8.1.1.7. sklearn.cluster.Ward

class sklearn.cluster.Ward(n_clusters=2, memory=Memory(cachedir=None), connectivity=None, copy=True, n_components=None, compute_full_tree='auto')

Ward hierarchical clustering: constructs a tree and cuts it.

Parameters:

n_clusters : int or ndarray

The number of clusters to find.

connectivity : sparse matrix.

Connectivity matrix. Defines for each sample the neigbhoring samples following a given structure of the data. Default is None, i.e, the hiearchical clustering algorithm is unstructured.

memory : Instance of joblib.Memory or string

Used to cache the output of the computation of the tree. By default, no caching is done. If a string is given, it is the path to the caching directory.

copy : bool

Copy the connectivity matrix or work inplace.

n_components : int (optional)

The number of connected components in the graph defined by the connectivity matrix. If not set, it is estimated.

compute_full_tree: bool or ‘auto’ (optional) :

Stop early the construction of the tree at n_clusters. This is useful to decrease computation time if the number of clusters is not small compared to the number of samples. This option is useful only when specifying a connectivity matrix. Note also that when varying the number of cluster and using caching, it may be advantageous to compute the full tree.

Attributes

children_	array-like, shape = [n_nodes, 2]	List of the children of each nodes. Leaves of the tree do not appear.
labels_	array [n_samples]	cluster labels for each point
n_leaves_	int	Number of leaves in the hiearchical tree.
n_components_	sparse matrix.	The estimated number of connected components in the graph.

Methods

fit(X)	Fit the hierarchical clustering on the data
fit_predict(X[, y])	Performs clustering on X and returns cluster labels.
get_params([deep])	Get parameters for the estimator
set_params(**params)	Set the parameters of the estimator.

__init__(n_clusters=2, memory=Memory(cachedir=None), connectivity=None, copy=True, n_components=None, compute_full_tree='auto')

fit(X)

Fit the hierarchical clustering on the data

Parameters:

X : array-like, shape = [n_samples, n_features]

The samples a.k.a. observations.

Returns:

self :

fit_predict(X, y=None)

Performs clustering on X and returns cluster labels.

Parameters:

X : ndarray, shape (n_samples, n_features)

Input data.

Returns:

y : ndarray, shape (n_samples,)

cluster labels

get_params(deep=True)

Get parameters for the estimator

Parameters:

deep: boolean, optional :

If True, will return the parameters for this estimator and contained subobjects that are estimators.

set_params(**params)

Set the parameters of the estimator.

The method works on simple estimators as well as on nested objects (such as pipelines). The former have parameters of the form <component>__<parameter> so that it’s possible to update each component of a nested object.

Returns:self :